Macrophages are immune cells crucial for immune response, tissue repair, and the removal of cancer cells. Scientists see macrophages as promising living therapeutics. However, to be effectively used for therapies, macrophages have to be grown to large numbers in laboratory culture without losing their special functions. So far, it was unclear if this is even possible. A team of scientists from Dresden and Marseille now reports that macrophages grown for long periods in laboratory conditions can function normally when transferred back into the body and are indistinguishable from the cells that never left the tissue. The results pave the way to new macrophage-based cell therapies. The study was published in the journal Nature Immunology on February 24, 2022.